1. Field of the Invention
This invention pertains to a torque limiter. More specifically the present invention pertains to a torque limiter having multiple compression springs. The torque limiter prevents torque above an adjustable torque-threshold from being transferred between two bodies of the device.
2. General Background
Torque limiters are used for a variety of purposes. One such purpose is to prevent damage to one or more components of an assembly by limiting how much torque can be transmitted from one component to another. By connecting the two components to each other via a torque limiter, only torque below a set torque-threshold of the torque limiter can be transferred through the torque limiter. For example, the first component could be a valve handle and the second component could be the shaft of a valve gate. By connecting the handle to a torque limiter, excessively high torque cannot be applied to the shaft of a valve gate by turning the valve handle.
One common type of torque limiter is a ball detent torque limiter. A ball detent torque limiter comprises a plurality of ball bearings that are spring biased into a plurality of detents. An excessively high torque will cause the balls to counteract the spring bias and move out of the detents. When the balls are out of the detents, the torque limiter generally becomes incapable of transferring torque (i.e., rotational slippage occurs). By adjusting the biasing force of the springs, the torque-threshold (i.e., the torque above which rotational slippage occurs) can be adjusted. Because of their compact size, ball detent torque limiters often use Belleville compression springs to generate the biasing forces. Nonetheless, most torque limiters have a relatively limited range over which the torque-threshold can be set or have cumbersome means for adjusting the torque-threshold.